Screening Tests

Antenatel Investigations

At your 1st visit the following tests will be requested:

Full blood examination

Blood group & antibody screen

Rubella antibody titre

Hepatitis B & C screen

Midstream specimen of urine

Glucose challenge test

Screening for trisomy 21 or Down syndrome is carried out at 12 weeks’ gestation by the Non-Invasive Prenatal Test (NIPT). This involves taking blood from the mother which is then analysed for the breakdown products of the DNA from the foetus. This allows screening for abnormalities such as Down syndrome (trisomy 21), trisomy 18, trisomy 13 and sex chromosome abnormalities. If an abnormality is detected through the screening blood test, an amniocentesis for full karyotype analysis is performed. Further information regarding the screening NIPT can be obtained from the Murdoch Childrens Research Institute by telephoning 03 8341 6201 or vcgs.org.au.
Screening for gestational diabetes mellitus (GDM) is also performed at 12 weeks gestation by administering the glucose challenge test (GCT) in the non-fasting state at this time. This consists of taking a 75 gram sugar drink and having a blood glucose level taken at 1 hour. If this is ≥6.5mmol/L, it is an indication for a fasting glucose tolerance test (GTT) at 28 weeks’ gestation to diagnose gestational diabetes. If ≥10.0mmol/L, it may be indicative of an underlying abnormality of glucose metabolism and a GTT should be done immediately.

A foetal anomaly scan is performed at 20 weeks gestation and you will be referred to a specialist obstetric ultrasonographer for this.
At 28 weeks gestation, the glucose tolerance test (GTT) is done to diagnose gestational diabetes and an antibody screen also if your blood group is Rhesus negative.
At 36 weeks gestation, a vaginal swab is taken to assess colonization with Group B Streptococcus and if positive will require you to have treatment with Penicillin during labour.